I am received the "PowerPoint is unable to load the data model" error that has been referenced in a few threads however, not only do I not have any SQL Services installed/running, I have not installed the October update either.
I'm running a Virtual machine (VMWare Vsphere hypervisor, Citrix XenDestkop receiver) with 4GB RAM and a personal VDisk configuration (so that my changes will be persistent). I can manage/manipulate data models when launching Excel as an administrator-level user but cannot as a normal user. There are no GPO's in play that would limit permissions and the add-on loads, but will not load a data model.
I've noted a few other reports similar to mine, one reporter resolved his issues by running a compatibility check (the troubleshoot compatibility option). I tried this track to no avail as well.
FWIW, the issue has followed me across a couple of virtual machines that were not identically configured (one connected to a VMWare View environment and two have connected to a Citrix environment), so this has me pretty well stumped at this point. I'm running Win 7 SP1, Office Professional 2013 (Locally installed in the image), MS virus (this is a config change, I had McAfee on a previous iteration exhibiting the same symptoms) with Adobe Reader, SCCM 2012 agent and VMWare tools as the only installed non-OS components.